This invention relates to apparatus for installing elongate articles such as terminal posts in apertures on substrates such as printed circuit boards and, more particularly, to a terminal post inserting component mountable on a reciprocable heat or ram of such apparatus to receive and support a terminal post and insert the post into an aperture in a substrate.
The terminal post inserting component of the present invention, referred to herein as a ram tip component finds particular utility in connection with inserting elongated performed terminal posts of square cross-section in apertures in a wiring board, which terminal posts are individually supported on an elongated carrier strip of flexible material. Accordingly, the invention will be described in detail hereinafter in conjunction with such terminal post structure and carrier strip post support. At the same time, it will be appreciated that the post inserting component can be employed in connection with the inserting of terminal posts having cross-sectional contours other than the square contour disclosed herein, and/or which posts are supported other than through the use of the particular carrier strip disclosed.
Apparatus has been provided heretofore in which terminal posts supported on a polyester carrier strip are transported step-by-step past a work station defined by a vertically reciprocable ram member carrying a post inserting ram tip component, and an anvil therebeneath and over which a circuit board is positioned for an aperture therein to be aligned with the ram tip component. A terminal post on the carrier strip is moved into position between the ram tip and an aperture in the circuit board while the ram is in its uppermost position and, thereafter, the ram descends for an opening in the ram tip to axially receive the upper end of the terminal post. During continued descent of the ram, the terminal post is stripped from the carrier strip by the ram tip component and is inserted into the circuit board aperture as the ram completes its downward stroke. Apparatus of this character and for this purpose is disclosed in U.S. Pat. No. 3,837,063 to Wright, issued Sept. 24, 1974.
The terminal posts to be inserted in a circuit board in the foregoing manner are extremely small in cross-sectional dimension and may have a length from about twenty to forty times the cross-sectional dimension, whereby the posts are readily bendable. Accordingly, extreme accuracy with respect to alignment between the ram tip and terminal post is necessary to assure that the post enters the ram tip. It will be appreciated that the ram tip is rapidly accelerated during initial descent thereof, whereby only a slight misalignment can cause the ram tip to hit the post so that the latter does not properly enter the ram tip if it enters at all. Such impact between the ram tip can result in loss of the post and/or damage to the ram tip. Further, such alignment between the ram tip and terminal post must be maintained following interengagement therebetween to assure alignment between the terminal post and the circuit board aperture for proper insertion of the terminal post therein. Minor misalignment between the post and ram tip either during initial interengagement therebetween or resulting from displacement of the post relative to the ram tip during movement thereof toward the circuit board, can result in loss of the terminal post, damage to the circuit board, and possible damage to the ram tip and ram. It will be appreciated that the ram tip carries the terminal post a considerable distance downwardly to the circuit board after pick-up of the terminal post from the carrier strip and, even if alignment between the terminal post and ram tip component is achieved during initial interengagement therebetween, displacement of the post relative to the ram tip can occur before the post reaches the circuit board aperture as the result, for example, of vibration and/or inadequate support of the post by the ram tip.
Heretofore, ram tip components employed with such terminal post inserting apparatus have included a nose portion defined by normally parallel spaced apart members intended to receive the upper end of a terminal post therebetween during initial downward movement of the ram tip. These nose members are somewhat flexible relative to one another about an imaginary axis spaced axially upwardly from the entrance end therebetween and into which the terminal post initially moves. Further, the nose members are intended to engage diametrically opposite sides of the terminal post upon movement of the post therebetween. It will be appreciated that such a post receiving construction affords no lateral support for the terminal post in the direction parallel to the nose members, whereby misalignment by displacement of the post laterally between the members during or following pick-up of the post is a potential problem. Further, in an effort to frictionally hold the terminal post between the members, the members are spaced apart a distance corresponding to the cross-sectional dimension of the post. Thus, variations in the latter dimension or the spacing of the members can cause problems with regard to retention of the post in the ram tip during movement of the post toward the circuit board, and can increase the likelihood of misalignment by displacement of the post laterally between the nose members. In this respect, for example, if the post is slightly over sized in cross-sectional dimension, the upper end thereof in effect engages and spreads the nose members apart, whereby only the upper end of the post is effectively held between the members. Accordingly, dropout of the post from the ram tip during movement thereof towards the circuit board is likely. If the terminal post is under sized in cross-sectional dimension, it will be appreciated that such dropout will occur as a result of no frictional interengagement between the post and the nose members. While the latter might be avoided to some extent by constricting the entrance end of the opening between the members, it remains that support for the terminal post would only be achieved at the point of constriction, whereby the potential dropout would still be a problem as would be the likelihood of displacement of the post laterally between the nose members as a result of the inadequate support thereof.
The foregoing problems result in loss of terminal posts by dropout and/or bending, circuit board damage from misalignment of posts and apertures in the circuit board, and damage or wear of the ram tip component and ram. These losses in turn result in excessive down time for maintenance, loss in production rate such as by interrupting a sequence of post insertions to clear the work area of loose parts or to insert a post in a location on the circuit board left empty by malfunction, and increased production costs as the result of post losses, maintenance costs, circuit board damage, and/or unacceptable end products.
Additionally, in connection with ram tip components heretofore provided, a different ram tip had to be attached to the ram, and/or the ram tip had to be accurately adjusted axially of the ram in order to provide for the apparatus to achieve proper depth of insertion of terminal posts of different length. Accordingly, production costs are increased by having to maintain a number of different inserting components, and by the down time required to achieve change-over for the apparatus to accommodate a new post length.